package com.agentlab.imitation.util;

import java.security.MessageDigest;
import java.util.Random;

public class MD5 {
	private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
		"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

/**
 * 转换字节数组为16进制字串
 * 
 * @param b
 *            字节数组
 * @return 16进制字串
 */

public static String byteArrayToHexString(byte[] b) {
	StringBuffer resultSb = new StringBuffer();
	for (int i = 0; i < b.length; i++) {
		resultSb.append(byteToHexString(b[i]));
	}
	return resultSb.toString();
}

private static String byteToHexString(byte b) {
	int n = b;
	if (n < 0)
		n = 256 + n;
	int d1 = n / 16;
	int d2 = n % 16;
	return hexDigits[d1] + hexDigits[d2];
}

public static String MD5Encode(String origin) {
	String resultString = null;

	try {
		resultString = new String(origin);
		MessageDigest md = MessageDigest.getInstance("MD5");
		resultString = byteArrayToHexString(md.digest(resultString
				.getBytes()));
	} catch (Exception ex) {

	}
	return resultString;
}

/**
 * 生成随即密码
 * @param pwd_len 生成的密码的总长度
 * @return  密码的字符串
 */
public static String genRandomNum(int pwd_len){
	 //35是因为数组是从0开始的，26个字母+10个数字
	 final int  maxNum = 36;
	 int i;  //生成的随机数
	 int count = 0; //生成的密码的长度
	 char[] str = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k',
	   'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
	   'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
	
	 StringBuffer pwd = new StringBuffer("");
	 Random r = new Random();
	 while(count < pwd_len){
	  //生成随机数，取绝对值，防止生成负数，
	 
	  i = Math.abs(r.nextInt(maxNum));  //生成的数最大为36-1
	 
	  if (i >= 0 && i < str.length) {
		   pwd.append(str[i]);
		   count ++;
	  }
	 }
	 return pwd.toString();
}
 

}